Insight of multifunctional Cu-alginate hydrogel membrane for precise molecule/ion separation applications

Membrane technology has garnered significant attention for its role in addressing the challenges of molecule/ion separation processes, yet it remains hindered by issues such as membrane fouling, including organic and biofouling. While calcium alginate (CaAlg) membranes have demonstrated remarkable antifouling and molecule/ion separation properties, they suffer from high swell ability and poor mechanical performance. This study introduces a one-step ion-crosslinking method to fabricate a series of copper alginate (CuAlg) hydrogel membranes. These membranes are then assembled into a dual-layer structure with a modified hydrophilic and mechanically robust microfiltration fiber support layer (MHSL). Notably, the CuAlg/MHSL membrane exhibits excellent separation performance, characterized by high selectivity and flux recovery rate. This membrane significantly enhances the long-term molecule/ion separation performance through improved mechanical strength, anti-swelling properties, and antimicrobial capabilities. In addition, the decreased thickness of the CuAlg/MHSL membrane enables higher flux rates, proving beneficial in cases of CaAlg membranes' inability to perform well under high-salt conditions. To further investigate the pore structure and anti-swelling mechanism of the CuAlg membrane, molecular dynamics (MD) simulations are conducted. Additionally, a life cycle analysis comparing the CuAlg hydrogel with various traditional polymers assesses their respective environmental impacts, highlighting the eco-friendliness of the hydrogel as a membrane substrate. These findings provide valuable insights for developing sustainable hydrogel membranes with stable performance and high separation efficiency in molecular/ion separation applications.